Correlating the interface structure to spin injection in abrupt Fe/GaAs(001) films

Understanding the effect of the interface on electrical spin injection is of great importance for the development of semiconductor spintronics. Fe/GaAs(001) is one of the leading systems for exploring these effects due to the small lattice mismatch. We report on the correlation between the experimentally observed Fe/GaAs(001) interface with the spin-transport properties. Using high-angle annular dark-field scanning transmission electron microscopy, we observe a predominantly abrupt interface with some regions of partial mixing also observed in the same film. We report that reproducible behavior with no bias-dependent polarization inversion was achieved for three-terminal devices. Using ab initio calculations of the experimentally observed interfaces, we show that the contribution to the transport from minority carriers is strongly dependent on the interface structure.